<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title>父相对，子绝对</title>
		<style type="text/css">
		*{
			margin: 0;
			padding: 0;
		}
			#header{
				height: 120px;
				background-color: blue;
			}
			#content{
				border: 3px red solid;
				height: 500px;
				position: relative;
				width: 800px;
				z-index: 1000;
				background-color: gainsboro;
			}
			#pos{
				position: absolute;
				right: -20px;
				bottom: 0px;
				height: 40px;
				width: 100px;
				background-color: darkgoldenrod;
				
			}
		</style>
	</head>
	<body>
		<div id="header"></div>
		<div id="content">
			<div id="pos">右下角广告</div>
		</div>
	</body>
</html>
